Method of making a physically and chemically active environment by means of a plasma jet and the related plasma jet

ABSTRACT

The method consists in the fact that from at least one external source ( 3 ) electromagnetic energy is conducted to at least one hollow electrode ( 1 ) with elements ( 14 ) locally increasing the density of electromagnetic energy, by which, inside the cavities of the electrode ( 1 ) and/or at its orifice and in the external environment an intensive discharge is generated. The plasma jet consists of at least one hollow electrode ( 1 ) of conductive or conductive and dielectric material with at least one element ( 14 ) locally increasing the density of electromagnetic energy inside the hollow electrode ( 1 ) and/or at its orifice and/or outside, which consists of a design element ( 12 ) and/or a physical element ( 17 ) acting in the transversal and/or the longitudinal direction with respect to the streaming working medium ( 5 ) and is further constituted by at least one source ( 3 ) or electromagnetic energy attached via the impedance adapting member ( 4 ) consisting of a system of regulatory transformation and transfer elements, onto the conductive part of the hollow electrode ( 1 ).

FIELD OF TECHNOLOGY

The invention concerns the method of making a physically and chemicallyactive environment by means of a plasma jet which permits thetransformation and the oriented transfer of electromagnetic energy inits different forms by means of a plasma, from the plasma jet to thetreated object.

BRIEF DESCRIPTION OF THE RELATED ART

For making a physically and chemically active environment utilised forthe treatment of objects or chemical compounds currently a broadspectrum of discharges generated in different ways on the basis ofelectromagnetic energy are used which in turn affect the activatedmedium or directly the treated objects.

From CZ 246982 a method of spatially oriented chemical activation of theworking gas by plasma is known in the region between the jet attachedvia the adapting member to the source of high-frequency (hf) energy witha non-symmetric output and the earthed electrode attached to the secondoutput of the above source. The use of the method is only limited to lowpressures, a gaseous working medium and an external plasmaticenvironment.

From PV 03925-90.J CZ—priority Sept. 9, 1990 and WO 95/11322modifications of the preceding mentioned method are known, characterisedby the fact that the generation of the discharge activating the workinggas passing through the jet takes place already inside the hollowelectrode in the working regime of the so-called high-frequency hollowcathode. In WO 95/11322, as against PV 03925-90.J CZ, the in turnsdischarge and non-discharge operation regime is utilised for sputteringthe material of the electrode, in PV 03925-90.J CZ a permanent magnetsituated axially symmetrically outside the jet is used for orientingplasmochemical processes. These two methods are only limited to lowpressures, a gaseous working medium and an external plasmaticenvironment.

According to WO 96/16531 the plasma is generated under low pressure in agaseous working medium, by means of the so-called hf hollow cathode oflinear geometry and plasmochemical processes are oriented by means of anadditional magnetic field of other than axial symmetry from permanentmagnets or electromagnets.

From SE 9302222-6 a modification of the preceding patents is known wherethe hollow electrode is fed from a microwave source.

The main drawback of the above methods and equipment for theirperformance is the fact that they are only limited to low pressures upto 10²⁻³ Pa, a gaseous working medium and an external plasmaticenvironment.

From Jpn. J. Appl. Phys. 33 (1994), L 197, a method of generating hfplasma under atmospheric pressure is known. In this case the hf.discharge is not generated in the electrode with a hollow geometry, buton a compact needle electrode inserted into the dielectric tube flownthrough only by the working medium in the gaseous state. Thedisadvantage of this method and equipment is the fact that the dischargeis generated on the fill needle electrode, by which the plasmochemicalprocesses of activating the streaming working medium are not so mucheffective as in the case of the discharge in the hollow electrode. It isapplicable only in a medium formed by the gaseous phase, where theoriented reaction channel is formed, capable of activating a furtherobject or the working medium.

In Plasma Sources Sci. Technol. 6, 1997, 468-477 a method is describedof generating a high-pressure discharge of the type of a direct currenthollow cathode in a gas without a flow through regime. The equipmentconsists of two electrodes, of which the cathode has a cavity with acylindrical symmetry with the inner diameter of about 0.2 to 0.7 mm andwhich is separated from the anode immediately linking up with thecathode hollow by a layer of the dielectric material. It is thus not aplasma jet because only gas is used without the flow through regime. Theequipment is not used for the activation or adaptation of any furtheractivated working medium or object and the electrodes are fed only froma direct current source.

From CZ 282566 B6 and Proc. of 18^(th) Symp. on Plasma Phys. andTechnology, Prague, 1997, 144-146, a method is known of generating avolume corona discharge in water or in water with admixtures between theelectrodes to which pulse voltage is applied, characterised by the factthat the intensity of the electric field in the proximity of at leastone of the electrodes increases by a partial coverage of this electrodeby a solid and/or gaseous dielectric, and on the surface of theelectrode spots are formed of the contact of the electrode material, thesolid and/or gaseous dielectric and/or water (the so-called “triplepoints” of different dielectric constants). The equipment for performingthis kind consists of a big cylindrical metal reactor which is at thesame time one electrode flown through slowly by the above liquid medium.The second rod-shaped electrode is placed longitudinally in the axis ofthat reactor. The method of generating the discharge can be carried outonly in the aqueous medium. The equipment is voluminous and only workswhen using a very efficient pulse source of direct current electricenergy (of the order of tens of MW in a pulse—Proc. of the 18^(th) Symp.on Plasma Phys. and Technology, Prague, 1997, 144-146).

All these methods are closely connected with an actual and highlyspecific arrangement of plasma generating equipment and highly specificworking conditions (working environment, medium, pressure, temperature,frequency of the excitation electromagnetic energy, power output of itssource, etc.). The facilities used in practice are usually narrowlyspecialised, spacious and they require a closed room (e.g. vacuumfacilities) or are highly requiring for energy consumption (e.g.plasmatrons—tens kW) or 15 for the method of discharge generation (suchas a pulse corona—tens of kW to MW in a pulse). Hitherto no possibilityhas existed of targeted, space narrowly directed, sufficiently fine, buteffective, superficial or small-volume adaptations of objects underhigher pressures (particularly in free atmosphere or in a liquidmedium), carried out by a single facility in the whole spectrum offrequencies of the source voltage.

SUBJECT MATTER OF THE INVENTION

The above drawbacks are removed by the method of generating a physicallyand chemically active environment by means of the plasma jet, accordingto the invention consisting in the fact that from at least one externalsource of performance of about 10⁰ to 10³ W and voltage amplitude of theorder of 10¹ to 10⁴ V with the possibility of its modulation at thefrequency range of DC (ss), low frequency (nf), high frequency (hf) ormicrowaves (vhf) electromagnetic energy is conducted to at least onehollow electrode flown through by the stream of the working medium inwhich an electromagnetic field is formed in the longitudinal and/ortransversal direction of the electrode cavity and/or its orifice, and atthe same time free carriers of the charge are generated by the action ofelements locally increasing the density of electromagnetic energy andcollision processes of particles in the working medium and on thesurface of the hollow electrode by which, inside tee electrode cavitiesor/and at its orifice and in the external medium an intense discharge isgenerated or a system of primary and filamentary discharges with theirown internal streaming which are carried by the flowing through workingmedium which are gradually activated and thus formed plasma, togetherwith the streaming and henceforth activating working medium flow throughthe hollow electrode and in the external medium at subsonic orsupersonic speed with contemporaneous generation of a pointed reactionchannel at the pressure of 10³ to 10⁶ Pa.

The transfer of electromagnetic energy into the discharge carried by theworking medium is matched adapted.

The working medium and the external medium is a gas, a liquid or theirmixtures or a mixture of solid particles with the gas, liquid or theirmixtures.

The process of plasma generation and the activation of the workingmedium is advantageously co-generated and controlled by another magneticfield formed from a permanent magnet and/or from an electromagnet ortheir system.

The plasma jet for generating a physically and chemically activeenvironment according to the invention consists in the fact that it isformed by at least one hollow electrode of conducting or conducting anddielectric material with at least one element locally increasing thedensity of electromagnetic energy inside the hollow electrode and/or atits orifice and/or outside which is constituted by a constructionelement and/or a physical element operating in the transversal and/orlongitudinal direction with respect to the streaming working medium andfurther it is constituted by at least one source of electromagneticenergy attached via the system of regulation, transformation andtransfer elements to the conducting part of the hollow electrode.

The design element consists of the rough surface of the electrodematerial and/or the cavity and/or the projection and/or point and/oredge placed inside the electrode cavity and/or outside and/or in itsorifice; and/or of openings and/or slits formed inside the hollowelectrode and/or a contact place of the conducting part of the electrodewith dielectric material.

The physical element is selected from a group consisting of thesupplementary electrode of different potential than the hollow electrodeand/or the source of electrically charged particles or particles excitedinto higher energy levels of excited particles and/or a source ofphotons or particles with high energies operating in the transversaland/or longitudinal direction with respect to the streaming workingmedium.

With an advantage a magnet and/or an electromagnet is placed inside oroutside the hollow electrode.

The hollow electrode is fixed to a non-conductive holder which permitsmanual or mechanical handling.

In this way it is possible to make four fundamental types of highlyvariable and dynamic high-pressure one pole (feeding the electrode withhf energy) or dipole (source of electromagnetic energy without bandlimitation) discharges or systems of discharges which can link up witheach other and which are blown out of the cavity of the plasma jet orwalls of its orifice and directed in the external environment. Thesefundamental types of discharges are as follows:

1. A high-pressure discharge or a system of discharges generated insidethe hollow electrode which is a constituent of the plasma jet and/orforms it, and is blown out of it or which is blown out of the walls ofits orifice and/or the system of its cavities (multicellular discharge).This discharge or the system of discharges can be characterised by twolimiting states:

a) The plasma is actively generated inside the electrode cavity only atthe negative part of the voltage amplitude on the electrode (the hollowelectrode is the cathode—from about the frequency of 1 kHz the plasmakeeps in the electrode cavity permanently).

b) The plasma is actively generated inside the electrode cavityirrespective of the voltage amplitude on the electrode (e.g. by theabove elements locally increasing the density of electromagneticenergy).

1. A high-pressure “aggravated” discharge or system of discharges whichis blown out from the hollow electrode from which it is at least partlyseparated by a layer of dielectric material or which is blown out fromthe walls of its orifice and/or the system of its cavities.

2. A high-pressure discharge or a system of discharges liking up withthe discharges of types 1 and 2, and which is generated by dielectricelements of the hollow electrode, will take place by:

c) polarisation and/or the accumulation of the polarisation charge onthe walls and edges of the dielectric tube or other dielectric elementsof the electrode jet,

d) increasing the density of electromagnetic energy on the transitionsconducting material —dielectric (and/or dielectric material of differentdielectric constant).

1. A high-pressure discharge or a system of discharges linking up withdischarges 1 to 3 outside the hollow electrode in the externalenvironment or the flickering of the plasma generated in discharges 1 to3.

The rise and permanent generation of the individual discharges orsystems of discharges by means of the above facility will take place onfulfilling the following design, working and existence conditions:

1. The rise of the first type of discharge will take place on conditionthat the middle free electron trajectory in the given working mediumunder the given pressure remains essentially lower and/or comparable inorder with the smallest dimensions of the plasma jet cavity and/or thedischarge space outside its orifice and, besides, at the direct-currentor low-frequency feeding of the plasma jet under the assumption that thesmallest dimension of the cross-section of the electrode cavity belarger than the minimum distance of the negative light from the cathode.

2. The second type of discharge is not limited by the mutual relation ofthe middle free trajectory of electrons in the given working mediumunder the given pressure and the smallest dimension of the cavitycross-section of the plasma jet constituting its inner discharge spaceand/or discharge spaces outside its orifice, just when the so-called“aggravated” type of discharge is used inside the hollow electrode, i.e.when the inner discharge space is separated from the conducting part ofthe electrode cavity by a layer of dielectric material, particularly forthe transmission of high-frequency energy.

The blown-out discharge, or the system of discharges from the orifice ofthe electrode jet can be, even despite its conspicuous speciesdiversity, partly characterised by the temperature of neutral particlesin the plasma approximated from the rotary temperature of the OHmolecule varying between 300 and 1000 K according to the chosen designvariant, the employed working medium and the method of application.

Under low pressures (about 10⁰-10³ Pa) in a gaseous or a plasmaticenvironment these discharges pass continuously into some known kinds ofdischarges blown out of the plasma jet of hollow geometry (a hollowcathode, etc.).

The method and equipment according to the invention are utilisable inany medium and at any pressure.

I can be utilised:

1. in a targeted way for the activation and modification of the gas,liquid, mixture of gas and liquid or liquid borne dust particles orsmall objects flowing through the plasma jet

2. for the modification of surfaces of objects

3. for the volume modifications of the treated object

4. for the modification of immersed or dispersed minor objects orcompounds situated in the treated objects

5. for the activation of a further working medium consequently affectingthe treated objects and/or compounds

6. for the change in the material of the plasma jet or its parts

7. for the plasmochemical synthesis of compounds in the solid, liquid,gaseous, plasmatic or mixed state

8. the employment of the invention is also possible on biologicalobjects (particularly at the high-frequency method of generating thedischarge) and other applications.

In manual work with the plasma jet immediate and direct checking ofplasmochemical processes and their effects on the treated object ispossible, which is excluded or considerably limited when the object isplaced in a plasmochemical reactor.

BRIEF DESCRIPTION OF THE DRAWINGS

In FIG. 1 the principle of the plasma jet is demonstrated for generatinga physically and chemically active environment and, at the same time,the simplest example of an advantageous design of the equipment.

In FIGS. 3 through 8, 9 a, 9 b, 10 a-10 d, 12 a, 12 b and 16 twodifferent design varieties of the hollow electrode are given.

In FIGS. 2, 11 and 13 a, b, c there are simple types of the plasma jet.

In FIGS. 14 and 15 design variants of the plasma jet are represented.

EXAMPLES OF VERSION

The examples of the design version of the hollow electrode and thegraphic presentation of the plasma jet.

The fundamental design variant of the hollow electrode 1 is a hollowcylinder with at least one element locally increasing the density ofelectromagnetic energy, which is e.g. the design element 12 constitutedby the roughed surface of cavity 13 of the electrode 1, or a noserepresented e.g. in FIG. 5 or a point in FIGS. 4, 5 or an edge, openingsor slits made in the hollow electrode 1 represented in FIGS. 3 and 4.

An element locally increasing the density of electromagnetic energy canalso be the physical element 17 which is introduced into the cavity 13of the electrode 1 or to its orifice (FIGS. 10b, d, 12 b, 15).

Another design variant is based on the preceding variants. Thefundamental variant of the hollow electrode 1 is completed by dielectricparts. The internal and/or external walls of the electrode/-s 1 are atleast partly covered with a layer of dielectric material 18 and/or asystem of full and/or hollow and/or porous dielectric materials 18surrounding the electrically conductive parts 19 and/or they are insidetheir cavities, as represented in FIGS. 12a, b, where 18 is dielectricmaterial and 19 the electrically conductive part.

The hollow electrode 1 is constituted by a system of cavities 13 made inthe electrode 1, as shown in FIGS. 5, 6. According to FIG. 7, cavities13 flown through by the working medium 5, are formed by spaces amongporous material 16, electrically conductive or non-conductive, which canbe balls or a net. Cavities 13 of the electrode 1 can also be formed bya plate wound into a spiral or a system of cylinders or their partsplaced in one another as represented in FIGS. 8, 9 a, b which, besides,can be shifted longitudinally with respect to each other, the cylindersituated in the centre not having to be hollow (a full point).

Another design variant is a system of segments 15 constituting a cavity13 or cavities 13 of the electrode 1, represented in FIGS. 10a, b, c, d.The individual segments 15 can be separated from each other bydielectric material 18 (FIGS. 10c, d) or they can be freely aggregated(FIGS. 10a, b) and separated from each other only by the working medium.

The design solution of the hollow electrode 1 represented in FIG. 16 hasa cluster or wad of fine fibres 29 or a swab of inorganic or organicmaterials such as glass, metal, pottery, cotton, horse hair, syntheticfibres, etc., fastened to the electrode 1 via the insulating dielectricmaterial 18, or another instrument with which it is possible to modifythe surface of the plasma treated object, such as a pencil or a gravingtool.

EXAMPLE 1

The simplest design variant put in effect of the plasma jet isrepresented in FIG. 1 for the case in which the ambient environment ofthe plasma jet is in the gaseous or plasmatic state, at the pressurehigher than about 10³ Pa, and/or in free atmosphere or at a pressurehigher than the atmospheric pressure. Electrode 1 is in the form of ahollow cylinder with a conical narrowing, with element 14 locallyincreasing the density of electromagnetic energy, constituted by thesharpened edges of the cavity orifice 13 of electrode 1. This type ispreferably employed in a system with an external counterelectrode or itserves as physical element 17 for the generation of the discharge insidecavity 13 and further electrode 1.

To the hollow electrode 1 through which the working gas 5 flows is, viathe impedance adapting member 4 consisting of a system of regulatory,transformation and transmitting elements, attached a ss, nf, hf or vhfsource 3. The hollow electrode 1 is fixed to a motile holder 2 ofdielectric material by means of which it is possible to control theplasma jet easily. At the point of the orifice of the hollow electrode 1a high density of electromagnetic energy arises which, besides, ispotentiated by stripping the spatial charge from the walls and points ofelectrode 1 by the streaming working medium 5, thus constituting apossibility of an easy ignition of the discharge 7 at the orifice of theelectrode 1. The discharge 7 penetrates in the negative currentalternation of the source voltage amplitude or in its negative pulse tothe cavity 13 of the electrode 1, where it generates a highly intensivetype of discharge 6. Discharges 6 and 7 activate the streaming medium 5.The thus generated plasma 8 streams through the cavity 13 of theelectrode 1 and through its orifice into the external environment, whereit constitutes a pointed reaction channel 9 in which the working gas 5is in turn activated, at the same time permitting the adaptation ofobjects in the outer environment. The originating interaction processes10 markedly feedback affect the process proper of plasma generation.

EXAMPLE 2

The plasma jet represented in FIG. 2 consists of a system of hollowelectrodes 1, of which at least one is the source of physically andchemically active environment and at least one is mechanically ordirectly manually controllable by means of the holder 2.

On the basis of a conflict of two and more reaction channels 9 from theindividual hollow electrodes 1 a resultant reaction channel 11 ariseswith formations of streaming plasma (usually much more voluminous thenthe primary reaction channels) which newly or further activated the fedworking medium 5.

EXAMPLE 3

FIG. 11 represents a schematic drawing of the plasma jet, when thematerial of the electrode 1 is cooled by the streaming medium 5 which isadvantageously utilised after fulfilling its cooling function to thesubsequent activation in some of the domains of physically andchemically activated environment 6 and 7, or it is utilised formodelling the shape of the reaction channel 9.

A part of the plasma jet of all above variants can be a permanent magnet20 and/or an electromagnet or their system located outside the plasmajet (FIGS. 13a-c) which participates in the formation and controls theprocess of plasma generation.

EXAMPLE 4

Another design variant with a combination of conductive and dielectricmaterial is represented in FIG. 14 and it can be used in any workingmedium, in the gaseous state or in the combination with a loose mixtureand/or with tiny droplets or vapours of a liquid, without employing acouterelectrode at the pressure of 10³ to 10⁶ Pa.

The electrode 1 is made of Ta, Mo, Pt, Ni, steel or any metal andnon-metal materials physically and chemically resistant electricallyconductive materials in the form of a hollow needle in whose mantlethere is a design element 12 formed by the opening. The electrode 1 isset in the carrier part 21 attached to the source 3, such as hf energy(13.56 MHz, 10-500 W) via the impedance adaptation article 4 and to thefeeder of the working gas 5. This carrier part 21 is fixed to anon-conductive holder 2 via its movable and rotation part 22. Theelectrode 1 is covered with the concentrating insulating capillary 23made of quartz glass with the possibility of controlling the depth ofimmersion of the hollow electrode 1 into the capillary 23 and at thesame time, it is shifted coaxially with a permanent magnet 20 with thepossibility of independent vertical movement by fixing via dielectricmaterial 18 to the carrying part 21.

The working medium 5 flows on the one hand inside the electrode 1, onthe other hand through the design element 12, through which it flowsinto the space between the electrode 1 and the wall of the capillary 23,thus allowing the cooling of the capillary 23. On the basis of physicalprocesses at the orifice of the hollow electrode 1 an intense hfdischarge 6 is initiated inside the cavity of the electrode 1—of thetype of the high-pressure virtual hollow cathode which is blown out fromits orifice and which is afterwards modelled by the capillary of quartzglass 23 and by the magnetic field generated by magnets 20. In thedischarges 6 and 7 the working medium 5 is permanently activated. Thethus streaming plasma 8 forms a pointed reaction channel 9 in theexternal environment. In applications below the level of the liquid, inthe space between the wall of the capillary 23 and the electrode 1 acomplementing hf discharge 24 is generated (capacitively coupled, acrossthe wall of the dielectric pipe, to the liquid), which causes theactivation of the working medium 5 flowing through this space. On theoutput from the electrode 1 the working medium 5—gas activated in thedischarges 6, 7 and 24 and the resulting salient discharge 25 formtogether a reaction channel 9.

EXAMPLE 5

Another advantageous design is the variant represented in FIG. 12b,where on the dielectric material 18 in the form of a capillary of quartzglass with inner diameter of about 0.01 to 5 mm a conductive layer 19(graphite, copper, etc.) is applied from the outer side. On theconductive layer 19 hf energy is conducted from the source (5 to 50 W,13.56 MHz) via the adaptation member. The discharge is initiated by thehigh density of electromagnetic energy at the orifice of the electrodenear the margin of the conducting layer 19 forming the hollow electrode1 and it is pulled into the cavity 13 formed by the dielectric material18. This design variant is suitable for the activation of a gaseousworking medium or a mixture of gas and a liquid (aerosol), particularlyfor highly local treatments of surface of objects or the treatment of amicrovolume of a liquid at the pressure of 10³ to 10⁶ Pa.

This valiant can be combined with a physical element 17 placed insidethe cavity of dielectric material 18, such as a tungsten or steel orcopper wire inserted transversally and/or longitudinally into the cavity13 (and which are on another potential than the hollow electrode 1).Then it is possible to activate with the plasma also a liquid workingmedium.

EXAMPLE 6

Another actual variant is represented in FIG. 15. It can be used in anyof the above external environments and in using any working medium atthe pressure of 10³ to 10⁶ Pa. Into the electrode 1 of an arbitraryshape attached to the source 3 of ss, nf, hf or vhf energy via theimpedance adapting member 4 and flown through by the medium 5 a suitablephysical element 17 is introduced from the side penetrating into thecavity 13 of the electrode 1. In the presented case the additionalelectrode 26 on another potential than the electrode 1 is chosen as aphysical element 17. This additional electrode 26 consists of amolybdenum, tantalum, tungsten and/or steel wire or a graphite rod andit is separated from the material of the electrode 1 by the capillary 27of quartz glass, pottery or teflon. Between the surface of the cavitywall 13 of the electrode 1 and the point of the additional electrode 26in the streaming environment of the working medium 5 a marked potentialgradient arises on whose basis the primary initiation discharge isgenerated (in the given case—an arc or a corona 28), which in turninitiates the intense discharge 6 inside the cavity 13. A secondaryintense discharge of the type of a high-pressure virtual hollow cathode6 and/or the flickering primary discharge 28 carried by the stream ofthe activated working medium 5 spouts from the orifice of the electrode1 and flickers or passes into another type of discharge 7 in the outerenvironment. The stream of the activated working medium 5 together withthe streaming plasma forms in the outer environment the pointed reactionchannel 9.

EXAMPLE 7

The plasma jets can be used for a fine finishing of details aftermechanical or laser machining, for a fine finishing or creating detailsin jewellery, goldsmith and glassmaker works or in artist andrestoration works, particularly in removing, sputtering or repairingpainting, writing or a protective layer on objects and/or theregeneration and preservation of these objects.

Fragments of much corroded archaeological glass with local layers ofprecipitates of the thickness up to 1 mm and layers of hydrated siliconoxide of the thickness of 20 to 200 micrometres with a substantialrepresentation of different deposited compounds causing a strongcoloration up to the opacity of the material were put in a 1% materialsolution of Complexon III. (C₁₀H₁₄O₈N₂Na₂.2H₂O) in distilled H₂O andexposed to the action of the equipment. Gradually at the pressure fromabout 10³ Pa and higher the following variants of the working mediumwere tested—Ar, N₂, Ar+N₂, Ar+H₂, Ar+SF₆, Ar+C₃F₈, Ar+C—C₄F₈, etc. Theoutput supplied from the source of hf energy varied within 50 to 200 W(13.56 MHz), the time of application in minutes. Glass archaeologicalfragments were cleaned in all tested cases after the application of theequipment.

Analyses of fragments after the application of the above describedmethod carried out on a scanning electron microscope with an energydispersing and wave dispersing analyser have shown that the essence ofobtained cleaning effect resulting in making the fractions of glasstransparent is a marked reduction of compounds containing Fe, Mn, Ca, P,K and others from the corrosion layers, but there was a mild enrichmentof the gel layer by Na. The application of particularly SF₆ as anadmixture of the working gas permitted a conspicuous reduction of theporosity of the surface of gel layers by their smoothing by means ofetching processes.

In the application of the method the overall rate and efficiency weobserved, but also the delicacy of cleaning the surface of corrodedglass (including the localising possibility of treatment on the surfaceof the fragment) outweighed many a times the effects of the classicalapplication by the plasma of inactivated liquid. This fact is due toquite different mechanisms of physico-chemical reactions taking place inthe contact of the activated medium or discharge with the liquid and atthe same time with the surface of the object.

INDUSTRIAL UTILITY

The invention can be utilised particularly in laboratories of physicaland chemical orientation, in the branch of material engineering, inmicroelectronics, in electrotechnical, engineering, chemical, textile,glass-making and cosmetic industries, in medicine, in ecology, forrestoring and preserving objects of the cultural heritage, in artactivity, etc. In the application of the invention, in the case ofemployment high-frequency energy (frequency higher than 1 MHz), noserious injury by electricity threatens any operator or any possibleliving object of the applications, but it must not be applied in thepresence of persons with cardiac pacemakers.

What is claimed is:
 1. A method of generating a physically andchemically active environment by means of a plasma jet, the methodcomprising conducting electromagnetic energy from at least one externalsource of output about 10⁰ to 10³ W and a voltage amplitude of the orderof 10¹ to 10⁴ V with the possibility of its modulation at frequencyrange DC (ss), low frequency (nf), high frequency (hf) or microwaves(vhf) to at least one hollow electrode, the at least one hollowelectrode having elements, the elements locally increasing a density ofelectromagnetic energy flown through by a stream of a working medium inwhich an electromagnetic field is generated in the longitudinal and/ortransversal direction of a cavity of the electrode or at its orificeand, at the same time, actions of the elements generating free carriersof the charge thereby locally increasing the density of electromagneticenergy and by collision processes in a working medium and on a surfaceof the hollow electrode by which, inside cavities of the electrodeand/or at its orifice and in the external environment an intensivedischarge originates or a system of primary and filamental dischargeswith their own internal streaming which are carried by the flowingworking medium which they gradually activate and a plasma thusgenerated, together with the streaming and further activating workingmedium flows through the hollow electrode and in the externalenvironment at a subsonic or supersonic speed with a simultaneousgeneration of a pointed reaction channel at the pressure of 10³ to 10⁶Pa.
 2. The method according to claim 1, wherein the transfer ofelectromagnetic energy into the discharge carried by the working mediumis impedance adapted.
 3. The method according to claim 1, wherein theworking medium and an external medium is a gas, a liquid or theirmixtures or a mixture of solid particles with a gas, a liquid or theirmixtures.
 4. The method according to claim 1, wherein the process ofplasma generation and activation of the working medium is cogeneratedand regulated by another magnetic field generated from a permanentmagnet and/or an electromagnet or their systems.
 5. The plasma jet forgenerating a physically and chemically active environment according toclaim 1, it is constituted by at least one hollow electrode ofconductive or conductive and dielectric material with at least oneelement locally increasing the density of electromagnetic energy insidethe hollow electrode and/or at its orifice and/or outside which isconstituted by a design element and/or a physical element acting in thetransversal and/or the longitudinal direction with respect to thestreaming working medium and it is further constituted by at least onesource of electromagnetic energy which is attached via the impedanceadjustment member constituted by a system of regulatory, transformationand transfer elements to the conductive part of the hollow electrode. 6.The plasma jet according to claim 5, wherein the design element isconstituted by a rough surface of material of the electrode or thecavity or a projection or a point or an edge placed inside the cavity ofthe electrode or outside or in its orifice; or openings or slits formedin the hollow electrode or openings or slits formed in the hollowelectrode or a contact place of the conductive part of the electrodewith dielectric material.
 7. The plasma jet according to claim 5,wherein the physical element is chosen from a group comprising anadditional electrode of a different potential than the hollow electrodeand/or a source of electrically charged particles or particles excitedto higher energy levels and/or a source of photons or particles withhigh energies acting in the transversal and/or longitudinal directionwith respect to the streaming working medium.
 8. The plasma jetaccording to claim 5, wherein the hollow electrode or outside the hollowelectrode a magnet and/or electromagnet is placed.
 9. The plasma jetaccording to claim 5, wherein the hollow electrode is fixed to anon-conductive holder permitting manual or mechanical control.